Marking instrument



FIG. 1 is a perspective view of a marking instrument, showing our new design;

FIG. 2 is an exploded perspective view thereof with the cap removed;

FIG. 3 is a front elevational view of FIG. 1;

FIG. 4 is a top plan view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a left side elevational view thereof;

FIG. 7 is a rear elevational view thereof; and

FIG. 8 is a bottom plan view thereof. 

The ornamental design for a marking instrument, as shown and described. 